The invention relates to water inlets in a marine propulsion gear case for supplying cooling water to the water pump for cooling the engine.
Conventional gear case water inlets are provided by holes in the gear case through which water is supplied to the water pump. In some applications, conventional water inlets are not capable of supplying sufficient pressure and water flow due to frothy or aerated water, typically due to obstructions on the bottom of the boat or to engine installation where the unit is mounted high on the transom, ventilating from the surface.
The present invention provides water intake means covering the conventional gear case water inlets and affording a much more aggressive water pickup. The water intake means in accordance with the invention provides positive water pressure and increased flow to the water pump, while having little affect on boat speed. The water intake has a forward opening edge for increasing water pickup, and a rearward trailing section holding the water captive around the normal inlets, forcing the water into the conventional gear case holes and to the water pump. The water intake of the invention can be mounted on gear cases with conventional cast-in water inlets or with conventional molded plastic inserts.
In one racing implementation, conventional inlets provided about 7 gallons per minute at 10 psi, at wide open throttle which corresponded to about 56 miles per hour. The water intake means in accordance with the invention provided 20 gallons per minute at 24 psi, at the same throttle and speed.
The invention has also been found to provide an additional advantage of enabling the motor to be raised by an inch and still be supplied with enough cooling water even though the water inlets are raised higher in the water. This one inch raising of the motor is desirable because it enables increased boat speed.